Quantitation of polar analytes using column-switching: Application to oxycodone and three metabolites in human plasma

Oxycodone Concentrations and Metabolic Ratios in Femoral Blood from Fatal Intoxications and Other Causes of Death using LC-MS-MS

Oxycodone (OC) is an opioid with strong analgesic effects widely used to treat acute and chronic pain. Interpretation of OC concentrations in postmortem cases is complicated due to tolerance and overlapping concentrations for fatal and non-fatal levels. In this study, our aim was to develop and validate a method for OC and its three metabolites: noroxycodone (NOC), oxymorphone (OM) and noroxymorphone (NOM) in postmortem femoral blood. Our goal was to define reference concentrations for intoxications and non-intoxications and investigate metabolic ratios in different causes of death. A rapid LC-MS-MS method using protein-precipitated postmortem blood was developed. Lower limit of quantitation was 0.005 μg/g blood for all analytes; upper limit of quantitation was 1.0 μg/g for OC and NOC and 0.25 μg/g for OM and NOM. The method displayed high precision (3.3-7.7%) and low bias (-0.3 to 12%). In total, 192 cases were analyzed and concentrations ranged from 0.005 to 13 μg/g for OC, 0.005 to 2.0 μg/g for NOC, 0.005 to 0.24 μg/g for OM, and 0.005 to 0.075 μg/g for NOM. We found a significant difference in OC concentration between the cases where OC contributed and those where it did not. In spite of that, we do not recommend the use of a specific blood concentration to distinguish fatal intoxications. Instead, the percentiles from our data set suggest that concentrations >0.2 μg/g are likely to have contributed to toxicity, but that concentrations as high as 0.3 might be tolerated without toxic effects. In addition, we also found that a low NOC/OC ratio could point toward an acute fatal intoxication. In conclusion, the OC concentration alone may not be sufficient to diagnose a fatal intoxication.

The Quantification of Oxycodone and its Phase I and II Metabolites in Urine

The purpose of this research was to develop and validate an analytical method for the detection and quantification of noroxymorphone-3β-D-glucuronide (NOMG), oxymorphone-3β-D-glucuronide (NOMG), noroxymorphone (NOM), oxymorphone (OM), 6α-oxycodol (αOCL), 6β-oxycodol (βOCL), noroxycodone (NOC) and oxycodone (OC) in urine by liquid chromatography tandem mass spectrometry to be used in a human study. The method was validated according to the Academy Standards Board Standard Practices for Method Development in Forensic Toxicology. The method was then applied to a single-dose pilot study of a subject. Urine samples were collected from the subject after ingesting 10-mg OC as an immediate-release tablet. Additionally, urine specimens (n = 15) that had previously been confirmed positive for OC were analyzed using the validated method. The calibration range for NOMG and OMG was 0.05–10 μg/mL; for all other analytes, it was 0.015–10 μg/mL. Validation parameters such as bias, precision, carryover and dilution integrity, all met the validation criteria. After the method was validated, urine samples from the first subject in the controlled dose study were analyzed. It was observed that OC, NOC and OMG contained the highest concentrations and were present in either the 0.5 or 1 h void. NOC and OMG were detected until the 48 h collection, while OC was detectable till the 24 h collection. Time to reach maximum concentration (T_max) in the urine was achieved within 1.5 h for OC and within 3 h for NOC and OMG. Maximum concentration (C_max) in the urine for OC, NOC and OMG was 3.15, 2.0 and 1.56 μg/mg, respectively. OC concentrations in authentic urines ranged from 0.015 to 12 μg/mL. Ranges for NOMG and OMG were 0.054–9.7 μg/mL and 0.14–67 μg/mL, respectively. A comprehensive method for the quantification of NOMG, OMG, NOM, OM, αOCL, βOCL, NOC and OC in urine was optimized and met the validation criteria. The concentrations of NOMG and OMG presented in this study provide the details needed in the forensic community to better comprehend OC pharmacokinetics.

A high-throughput bioanalytical assay to support pharmacokinetic interaction study of oxycodone and diazepam in Sprague Dawley rats

Benzodiazepines potentiate respiratory depression when combined with an opioid leading the U.S Food and Drug Administration (FDA) to recommend updating the labels of these products with a boxed warning for respiratory depression with co-use. Potential respiratory depression upon co-administration of opioids with some psychotropic drugs is not well understood. The FDA is currently investigating various psychotropic drug interactions with the commonly used opioid, oxycodone, in a rat model assessing respiratory depression. Pharmacokinetic and/or pharmacodynamic (PK/PD) interaction between oxycodone and diazepam was evaluated in a positive control arm of these experiments. Understanding the systemic exposure of these drugs alone and in combination exposures was used to identify PK/PD interactions. The authors developed a simple, high throughput liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay for the simultaneous determination of oxycodone and diazepam in rat plasma. Sample preparation was performed in 96-well protein precipitation plates using acetonitrile. Processed samples were analyzed using a C₁₈ column with a gradient mobile phase composed of 2 mM aqueous ammonium formate with 0.1% formic acid and acetonitrile. A Thermo TSQ Quantum Ultra AM triple quadrupole mass spectrometer with multiple reaction monitoring (MRM) mode was used to acquire data. The method was validated for selectivity, specificity, linearity, precision and accuracy, dilution integrity and stability. The validated LC-MS/MS assay was utilized for quantifying oxycodone and diazepam in concomitantly treated Sprague Dawley (SD) rats.

A high-throughput bioanalytical method for the simulataneous determination of oxycodone and diazepam to support the evaluation of respiratory depression in rats upon co-administration of oxycodone and diazepam.

Simultaneous determination of acetaminophen and oxycodone in human plasma by LC-MS/MS and its application to a pharmacokinetic study

A simple and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for simultaneous determination of acetaminophen and oxycodone in human plasma. Acetaminophen-d4 and oxycodone-d3 were used as internal standards. The challenge encountered in the method development that the high plasma concentration level of acetaminophen made the MS response saturated while the desired lower limit of quantification (LLOQ) for oxycodone was hard to reach was well solved. The analytes were extracted by protein precipitation using acetonitrile. The matrix effect of the analytes was avoided by chromatographic separation using a hydrophilic C₁₈ column coupled with gradient elution. Multiple reaction monitoring in positive ion mode was performed on tandem mass spectrometer employing electrospray ion source. The calibration curves were linear over the concentration ranges of 40.0–8000 ng/mL and 0.200–40.0 ng/mL for acetaminophen and oxycodone, respectively. This method, which could contribute to high throughput analysis and better clinical drug monitoring, was successfully applied to a pharmacokinetic study in healthy Chinese volunteers.

Determination of oxycodone and its major metabolites noroxycodone and oxymorphone by ultra-high-performance liquid chromatography tandem mass spectrometry in plasma and urine: application to real cases

Background:

Oxycodone is a narcotic drug widely used to alleviate moderate and severe acute and chronic pain. Variability in analgesic efficacy could be explained by inter-subject variations in plasma concentrations of parent drug and its active metabolite, oxymorphone. To evaluate patient compliance and to set up therapeutic drug monitoring (TDM), an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) assay was developed and validated for the parent drug and its major metabolites noroxycodone and oxymorphone.

Methods:

Extraction of analytes from plasma and urine samples was obtained by simple liquid-liquid extraction. The chromatographic separation was achieved with a reversed phase column using a linear gradient elution with two solvents: acetic acid 1% in water and methanol. The separated analytes were detected with a triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI).

Results:

Separation of analytes was obtained in less than 5 min. Linear calibration curves for all the analytes under investigation in urine and plasma samples showed determination coefficients (r

Conclusions:

Rapid extraction, identification and quantification of oxycodone and its metabolites both in urine and plasma by UHPLC-MS/MS assay was tested for its feasibility in clinical samples and provided excellent results for rapid and effective drug testing in patients under oxycodone treatment.

Rugged and accurate quantitation of colchicine in human plasma to support colchicine poisoning monitoring by using turbulent-flow LC–MS/MS analysis

Background: Colchicine is a common drug used in inflammatory diseases. The narrow therapeutic index requires fast and reliable techniques for its quantitation. An online, automated sample preparation using TurboFlow™ technology combined with triple-stage quadrupole MS detection was applied to identify colchicine in human plasma and follow intoxications. Methodology: Plasma samples (200 µl) were mixed with deuterated colchicine and protein precipitation ZnSO4 solutions. After centrifugation, supernatants were extracted onto a Cyclone P TurboFlow column and eluted onto a narrowbore Hypersil™ GOLD column with a methanol/water gradient. Analytes were monitored in SRM mode (positive electrospray). Results: Total run time was 9.5 min. Calibration curves ranged from 0.342 to 17.1 ng/ml, with significant linearity (R2 >0.99). Inter- and intra-assay precisions were <16.8% and accuracy was 84.4–110%. Conclusion: This method is suitable for monitoring intoxication in patients undergoing chronic treatment and is routinely applied to toxicological samples.

Determination of oxycodone, noroxycodone and oxymorphone by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry in human matrices: in vivo and in vitro applications

The opioid analgesic oxycodone is widely abused and increasingly associated with overdose deaths. A sensitive analytical method was developed for oxycodone and its metabolites, noroxycodone and oxymorphone, in human plasma, urine (±enzymatic hydrolysis at 50°C for 16 h) and liver microsomes (HLMs). Liquid-liquid extraction was followed by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. The calibration range was 0.2-250 ng/mL for plasma and HLM and 10-5000 ng/mL for urine. Intra- and interrun accuracies were within 13.3% of target; precisions were within 12.8% for all matrices. Recoveries from plasma were: oxycodone, 75.6%; noroxycodone, 37.4% and oxymorphone, 18.2%. Analytes exhibited room temperature stability in plasma and urine up to 24 h, and freeze-thaw stability in plasma up to three cycles. In 24-h hydrolyzed urine from subjects administered intranasal oxycodone (30 mg/70 kg, n = 5), mean concentrations (ng/mL) and % daily doses excreted were: oxycodone, 1150, 6.53%; noroxycodone, 1330, 7.81% and oxymorphone, 3000, 17.1%. Oxycodone incubated with HLM produced more noroxycodone than oxymorphone. With a panel of recombinant human cytochrome P450s (CYPs), CYP2C18 and CYP3A4 produced the most noroxycodone, whereas CYP2D6 produced the most oxymorphone. These results demonstrate a new method suitable for both in vivo and in vitro metabolism and pharmacokinetic studies of oxycodone.

Determination of cocaine and metabolites in hair by column-switching LC-MS-MS analysis

A method for rapid, selective, and robust determination of cocaine (CO) and metabolites in 5-mg hair samples was developed and fully validated using a column-switching liquid chromatography-tandem mass spectrometry system (LC-MS-MS). Hair samples were decontaminated, segmented, incubated overnight in diluted HCl, and centrifuged, and the diluted (1:10 with distilled water) extracts were analyzed in positive ionization mode monitoring two reactions per analyte. Quantifier transitions were: m/z 304.2→182.2 for CO, m/z 290.1→168.1 for benzoylecgonine (BE), and m/z 318.2→196.2 for cocaethylene (CE). The lower limit of quantification (LLOQ) was set at 0.05 ng/mg for CO and CE, and 0.012 ng/mg for BE. Imprecision and inaccuracy at LLOQ were lower than 20 % for all analytes. Linearity ranged between 0.05 and 50.0 ng/mg for CO and CE and 0.012 and 12.50 ng/mg for BE. Selectivity, matrix effect, process efficiency, recovery, carryover, cross talk, and autosampler stability were also evaluated during validation. Eighteen real hair samples and five samples from a commercial proficiency testing program were comparatively examined with the proposed multidimensional chromatography coupled with tandem mass spectrometry procedure and our reference gas chromatography coupled to mass spectrometry (GC-MS) method. Compared with our reference GC-MS method, column-switching technique and the high sensitivity of the tandem mass spectrometry detection system allowed to significantly reduce sample amount (×10) with increased sensitivity (×2) and sample throughput (×4), to simplify sample preparation, and to avoid that interfering compounds and ions impaired the ionization and detection of the analytes and deteriorate the performance of the ion source.

Recent advances in column switching sample preparation in bioanalysis

Column switching techniques, using two or more stationary phase columns, are useful for trace enrichment and online automated sample preparation. Target fractions from the first column are transferred online to a second column with different properties for further separation. Column switching techniques can be used to determine the analytes in a complex matrix by direct sample injection or by simple sample treatment. Online column switching sample preparation is usually performed in combination with HPLC or capillary electrophoresis. SPE or turbulent flow chromatography using a cartridge column and in-tube solid-phase microextraction using a capillary column have been developed for convenient column switching sample preparation. Furthermore, various micro-/nano-sample preparation devices using new polymer-coating materials have been developed to improve extraction efficiency. This review describes current developments and future trends in novel column switching sample preparation in bioanalysis, focusing on innovative column switching techniques using new extraction devices and materials.